To date, a terminal structure including a base material, a wiring conductor film disposed on the base material, an outer electrode disposed on the surface of the wiring conductor film, a resist film with which the surface of the base material and the surface of the wiring conductor film are covered, and a solder bump disposed on the surface of the outer electrode (Patent Document 1).
In this regard, as disclosed in Patent Document 1, when a conductive bonding material, e.g., solder, is bonded to the outer electrode, a method (over resist treatment), in which the outer edge of the wiring conductor film or the outer electrode is covered with a resist film, is adopted in general for the purpose of preventing the wiring conductor film or the outer electrode, which is formed on the base material, from peeling off the base material.
However, Au which constitutes the outer electrode gets wet with solder easily, and when the solder is bonded to the outer electrode, there is a concern that the solder may infiltrate into the interface between the surface of the outer electrode and the resist layer and the surface of the outer electrode may serve as a start point of peeling of the resist layer subjected to the over resist treatment.
Meanwhile, there is also a clearance resist type terminal structure in which a predetermined clearance is located between the resist layer and the outer electrode for the purpose of suppressing such peeling of the resist film (Patent Document 2).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-74487
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2013-98507